In 2011, Virgin Atlantic conducted a study that revealed 55% of respondents had heightened emotions on flights, with 41% of the men surveyed saying they had used a blanket to hide their tears.

As a result, the airline started issuing “emotional health warnings” before in-flight films.

At the time, Virgin Atlantic film critic Jason Solomons said it was all to do with the unfamiliar environment we find ourselves in, and the flurry of emotions that brings.

“On a flight, we’re isolated, leaving loved ones or aching to be reunited with them,” he said.

“We’re nervous, we’re tired, we might have had a drink at a time we usually wouldn’t. If we see an image, a scene that reflects our emotional state, frankly we’re suckers. Flying and films is a heady cocktail, the images and feelings so close to your eyeballs, so intimate.”

Some research seems to suggest that flying does strange things to our bodies, like affect our mood, mess with our senses, and make us itch more.

This isn’t that surprising when you think about how the low air pressure can reduce the amount of oxygen in your blood by up to 25%, and the fact the air conditioning makes the environment incredibly dry.

Mild hypoxia – a deficiency in oxygen – can lead us to do strange things because it can affect our thoughts and ability to make decisions. So it’s no wonder we may feel a little vulnerable, especially if you’re travelling alone, surrounded by strangers, locked in a metal tube for several hours.

Some evolutionary scientists believe crying is a bonding behaviour we’ve developed over centuries. Crying in theory makes other people feel sorry for you and comfort you, which forms social bonds.

So perhaps, when in an unusual, vulnerable environment, our primitive behaviour takes over and tries to help us forge allies.

On the flip side, adults rarely cry in public, and instead wait until they are alone.

In fact, some research suggests adults wait until they are behind the wheel of a car to have a good cry, because their solitude triggers their bad feelings, and they can finally let it all out.

Sitting down in your plane seat could have a similar effect. Although you’re surrounded by people, it can sometimes feel like you’re all alone.

Another factor could be the fact we have fewer distractions while on a plane. While normally at home you might watch TV, play on your phone, and talk to someone all at the same time, on a plane you don’t have all of those options.

With nobody texting you, and everyone around you being relatively silent, it’s easier to focus all your attention on a film. Add in the likelihood of heightened emotions, and you’ve got a recipe for weeping.

Of course, there is also the chance you are just tired. Getting up at the crack of dawn and navigating around an airport is no fun, and being exhausted can make us more emotional anyway.

There are no specific studies looking into why we cry on planes yet, but if you find yourself doing so, remember you’re not alone – you’re simply a member of the “Mile Cry Club.”